I accidentally double installed my macbook pro snow leopard? What to do? Please help!?

I was trying to reset my administrator pword b/c it wouldn't let me proceed with an installation without it. So i put in the mac installation cd and accidentally began reinstalling on my mac. It is currently halfway through isntallation, as I can't find a way to force quit or eject it. And it says my computer may not start if i quit installation midway. What is the consequence of this (since i didnt go through all the steps of a true reinstallation)? Is there a way to fix this? please help!!!